Process and apparatus for monitoring synchronizing generators



H. E. BESTE PROCESS AND APPARATUS FOR MONITORING Sept. 7, 1948.

SYNCHRONIZING GENERATORS Filed Feb. 13, 1945 94430 SEC. *L5- Q00 CYCLE SAW atenteol Sept. 7, 194g PROCESS AND APPARATUS FOR MONITOR- ING SYNCHRONIZING GENERATORS Harold Edward Beste, East Rutherford, N. J., as-

signor to Allen B. Du Mont Laboratories, Inc., Passaic, N. J., a corporation of Delaware Application February 13, 1945, Serial No. 577,699

(ci. S- 9) 10 Claims.

This invention relates to a device and process for monitoring generators that are synchronized. The invention is particularly useful for monitoring sawtooth wave generators used in television 'circuit was determined by counting the number of pulses, on the sawtooth wave form, generated by the previous circuit which fired it. By the above method it was necessary to switch to one oscillator at a time, adjust the sweep, and adjust synchronization controls. the synchronizing pulses and wave forms to the monitoring device was necessarily complicated in Ythat the sweep frequency also had to be changed by switching in different components when Vswitching from one oscillator to another.

rBy the present invention the operation of all of the frequency dividing stages of a synchronizing generator can be shown simultaneously in -such a way that it is immediately known when adjustments are needed, and also when proper adjustments have been made. By this inven- -tion the monitoring system is greatly simplified, extra tubes, switches and other components formerly used are eliminated, and a much more satisfactory monitoring system is provided.

The invention may be understood from the description in connection with the accompanying drawing, in which:

Fig. 1 is `a somewhat diagrammatic arrangement of apparatus for carrying out the invention; and

Figs. 2 and 3 are diagrams showing patterns that appear upon the faces of cathode-ray tubes that enable thev oscillators to be monitored.

In the drawing, reference characters I and 2 l indicate cathode-ray tubes each having a cathode 3, control grid d, and first and second anodes 5 and 6. Tube I has vertical deection plates i and 8 and horizontal deflection plates 9 and IIJ. Tube 2 has vertical deflection plates I I and I2, and horizontal deflection plates I3 and I4. The

`tube I is provided with the usual luminous screen l? on the inside surface of the end thereof which is caused to be scanned by the beam or ray I5 of electrons. The tube 2 is provided with the The switching of l v2 screen I 8 which is scanned by the ray or beam I6.

Lead 26 extends from the oscillator 20 to the control grid 4 of tube I, lead 21 extends from the oscillator 2l to the vertical deection Aplate 'I, and the lead 28 extends from the oscillator 22 to the vertical deflection plate 8. The 4horizontal deection plate 9 is grounded and a lead 29 extends from the oscillator 23 to the horizontal deflection plate I0. Lead 3| extends from the oscillator 23 to the vertical deflection plate I I of tube 2, lead 32 extends from oscillator 24 to the vertical delection plate I2, lead 33 extends from oscillator 25 to the horizontal deflection plate I3, and the horizontal deflection plate I4 is grounded.

A cycle source of power 35 is connected to the control grid d of tube 2 by lead3l.v

The operation will be described specifically, using frequencies that are at present standard although the invention is useful with other frequencies.

The horizontal sweep on tube2 is producedby applying a sawtooth voltage of 60 cycles per second from oscillator 25 to the horizontal deflection plate I3. Its length of time is one-sixtieth of a second as indicated by the horizontal arrows at the bottom of Fig. 2. This sixty cycle sawtooth sweep is broken up into three sawtooth wave forms on the screen I8 of cathode-ray tube 2, as indicated by the three groups of ve vertical lines each in Fig. 2. This occurs because the cycle sawtooth wave signal from oscillator 24 is applied to the vertical deflection plate I2 of oscillator 2. That is, the beam I6 is deiiected vertically three times during each one-sixtieth second horizontal sweep, or one time each one hundred and eightieth of a second, by the sawtooth shaped impulses from oscillator 24. This is shown in Fig. 2 by three groups of vertical lines in Fig. 2, each one of these lines occurring in one nine hundredth of a second due to the 900 per second sawtooth shaped impulses from oscillator 23 being applied to vertical deflection plate II.

The horizontal sweep of beam I5 of tube I is produced by applying a sawtooth voltage -of 900 cycles from oscillator 23 to the horizontal deflection plate I0 of tube I by lead 29. This 900 cycles per second sweep is divided into ve portions as viewed on the screen of tube I by applylng a 4500 cycle sawtooth wave from oscillator 22 to the vertical deflection plate 8. Each one of these 4500 per second sawtooth waves is represented in Fig. 3- as a group of seven linesin- Veluded between the sloping line marked 4500 saw. `In turn each one of these 4500 cyclesaw 3 tooth waves is divided into seven individual sawtooth waves by coupling the 31,500 cycle sawtooth wave out of blocking tube oscillator 2I to the vertical deflection plate 'I of tube I' by lead 21. Each one of these 31,500 per second sawtooth waves is represented in Fig. 3 as a group of fine dots, one of these groups being included between arrows and marked l31,500 saw."

Each 31,500 cycle sawtooth wave is modulated by coupling the 157,500 cycle sine wave output from oscillator 20 to the grid l of tube I. This results in producing five alternate dark and bright spots in each one of the 31,500 cycles per second lines as shown in Fig. 3.

Another way of understanding what is depicted in Fig. 3 is by noticing that when the'900 cycle per second impulses are applied by lead 29 to the horizontal deflection plate I0, the result is a sawtooth sweep along the horizontal axis of the tube I at the rate of 900 cycles per second.

The 4500 cycles persecond impulses from oscillator-22 'which are applied to the horizontal deflection plate 8 of tube I produce the ve rows of lines, one of these yrowsbeing marked "4500-saw. nFig. 3.

Each 'one of the -five4500 cycle 4per second' impulses is divided into seven vertical lines by the .31,500 cycle per second yimpulses from oscillator .2l that are applied by lead 211 to the vertical delection'plate 1. One of these lines is labelled at the upper right hand corner of Fig. 3,'there being thirty-five of them for each 900 cycle per second impulse from oscillator 23.

.The oscillator 20 applies a cathode-ray beam v.blanking signal to the grid 4 of tube I at one hundred fifty-seven thousand live hundred times lper second. The blanking impulses vproduce thedots shown in Fig/3 at this rate which isve timeslper -impulse'applied by lead 21 frorn oscillatorZI 'to plate 'I of tube I.

synchronizing generators are usually locked-in to thefpower line frequency, such as 60 cycles per secondgfor example. In order to `check the .phase relationship between the=60 cycle oscillator 2.5 .andthe power line frequency,.indicated Vdiagrammatically by "block`35, the lead 36 is connected from the power line to the grid 4 `of tube 2 in such a way that this grid is modulated slightly by .a small portionofhal'f Yof the60 cycle power line frequency. .The result of'this modulation is that `a small portion of the wave forms on the screen .IBoftube 2 appears slightly darkened. This :darkened portion will remain in one position when 'lock-in prevails. When the oscillator 25 departs from the power line frequency the darkened vportion will :move horizontally along the wave forms indicated in Fig. 2.

vIt will be obvious that thesignals ldepicted in Figs-2 and 3^-will be Vas shown therein, only when ythe oscillators 20 to 25 arering correctly. and` that since the respective signals are readily identil-led with respect to the oscillators which produce them any irregularity therein instantly reveals that the corresponding oscillator needs-ad- -rjusting. In this'way the device serves as a moni- -ed sawtooth wave generating oscillators the fre- -quencyof each one of which is vanintegral multiple of a preceding one, which comprises a cathode-ray tube and a direct lead from each one of 4 at least three of said oscillator to a different deection electrode of said tube.

2. A device for monitoring a series of connected sawtooth wave generating oscillators the frequency of each one of which is an integral multiple of a preceding one, which comprises a. cathode-ray tube and a direct lead `from Aeach one of at least three of said oscillators Vto a different deflection electrode of said tube, two of said electrodes being a pair which deflect the beam of said tube in opposite directions.

3. A devicefor monitoring a series of connected sawtooth wave generating oscillators the frequency of each one of which is an integral multiple of a preceding one, which comprises a cathode-ray tube and a direct lead from each one of at least three of said oscillators to a different deilection electrode of said tube, two of said electrodes being a pair which deflect the beam of said tube in opposite directions and a third one being adapted to deect said beam atanang-le to the deflection of saidpair.

l'4. A device for monitoring a seriesofconnected sawtooth wave generating oscillators the frequency of each one -of which is anintegral multiple of a preceding one, which-comprises a cathode-ray tube and a direct lead from each one of at least three of said oscillators toa different` deflection electrode of said tube, two ofi-said electrodes being a pair which deect thebeam of said tube in opposite directions, a third one being adapted to deflect said beam atan-angle vto the deflection of said pair and the fourth -one being grounded.

5. A device for monitoringa series of connected sawtooth wave generating oscillators the frequency of each one of which is an integral multiple of a'preceding one, which ycomprises a plurality of cathode-ray tubes anda lead from each one of at least ve of said oscillators Ato a differality of cathode-ray tubes and-a lead from each one of at least iive of said oscillators to.a different deflection electrode of said tubes, one of thedeflection electrodes of each one of saidcathoderay tubes being grounded.

8. A device for monitoring-a seriesofvconnectedsawtooth wave generating oscillators thefrequency-of each oneof which is an integral multiple of a preceding one, which comprises =a cathode-ray tube, a direct lead from each oneof at least three of said oscillators to a diierent'deiiection electrode of said tube and a'source of power of the sameffrequency as that of the lowest frequency of said oscillators `connected to the control grid of said tube.

9. A device for-monitoring a series offconnect- .ed sawtooth wave generating oscillators ythe fre- -ality of cathode-ray tubes, alead from eachone of at least five of said oscillators to a different de- `lection electrode of said tubes and a lead from the oscillator of highest frequency of saidplural- 5 ity of oscillators to the control grid of one of said tubes.

10. A device for monitoring a series of connected sawtooth Wave generating oscillators the frequency of each one of which is an integral multiple of a preceding one, Which comprises a cathode-ray tube, a direct lead from each one of at least three of said oscillators to a different deection electrode of said tube, a source of power of the same frequency as that of the lowest fren quency of said oscillators connected to the control grid of said tube and a lead from the oscillator of highest frequency of said plurality of oscillators to the control grid of one of said tubes.

HAROLD EDWARD BESTE.

REFERENCES CITED The following references are of record in the le of this patent:

UNL'TED STATES PATENTS 

